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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2012 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: PersistentObjectContainerLoader.html 883 2014-05-07 02:45:34Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.pobj.vaadin;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import com.vaadin.server.VaadinSession;<a name="line.10"></a>
<span class="sourceLineNo">011</span><a name="line.11"></a>
<span class="sourceLineNo">012</span>import org.dellroad.stuff.pobj.PersistentObject;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import org.dellroad.stuff.vaadin7.AbstractSimpleContainer;<a name="line.13"></a>
<span class="sourceLineNo">014</span><a name="line.14"></a>
<span class="sourceLineNo">015</span>/**<a name="line.15"></a>
<span class="sourceLineNo">016</span> * Facilitates populating a {@link AbstractSimpleContainer} with data from {@link PersistentObject}<a name="line.16"></a>
<span class="sourceLineNo">017</span> * and automatically updating it when that {@link PersistentObject} changes.<a name="line.17"></a>
<span class="sourceLineNo">018</span> *<a name="line.18"></a>
<span class="sourceLineNo">019</span> * &lt;p&gt;<a name="line.19"></a>
<span class="sourceLineNo">020</span> * The constructor requires a {@link Generator} to generate, from the {@link PersistentObject}<a name="line.20"></a>
<span class="sourceLineNo">021</span> * root object, the Java objects that populate the {@link AbstractSimpleContainer}.<a name="line.21"></a>
<span class="sourceLineNo">022</span> * &lt;/p&gt;<a name="line.22"></a>
<span class="sourceLineNo">023</span> *<a name="line.23"></a>
<span class="sourceLineNo">024</span> * &lt;p&gt;<a name="line.24"></a>
<span class="sourceLineNo">025</span> * &lt;b&gt;Note:&lt;/b&gt; Instances of this class start out in a non-listening state. You must invoke {@link #connect connect()}<a name="line.25"></a>
<span class="sourceLineNo">026</span> * to start listening to the {@link PersistentObject} and (re)load the container contents.<a name="line.26"></a>
<span class="sourceLineNo">027</span> * You should invoke {@link #disconnect} whenever the container is no longer used to avoid a memory leak.<a name="line.27"></a>
<span class="sourceLineNo">028</span> * Typically, {@link #connect connect()} and {@link #disconnect} are invoked from the<a name="line.28"></a>
<span class="sourceLineNo">029</span> * {@link com.vaadin.ui.Component#attach attach()} and {@link com.vaadin.ui.Component#detach detach()} methods (respectively)<a name="line.29"></a>
<span class="sourceLineNo">030</span> * of the GUI widget that is using the container.<a name="line.30"></a>
<span class="sourceLineNo">031</span> * &lt;/p&gt;<a name="line.31"></a>
<span class="sourceLineNo">032</span> *<a name="line.32"></a>
<span class="sourceLineNo">033</span> * @param &lt;T&gt; type of the persistent object<a name="line.33"></a>
<span class="sourceLineNo">034</span> * @param &lt;K&gt; the type of the Java objects that back each {@link com.vaadin.data.Item} in the container<a name="line.34"></a>
<span class="sourceLineNo">035</span> */<a name="line.35"></a>
<span class="sourceLineNo">036</span>@SuppressWarnings("serial")<a name="line.36"></a>
<span class="sourceLineNo">037</span>public class PersistentObjectContainerLoader&lt;T, K&gt; {<a name="line.37"></a>
<span class="sourceLineNo">038</span><a name="line.38"></a>
<span class="sourceLineNo">039</span>    private final AbstractSimpleContainer&lt;?, K&gt; container;<a name="line.39"></a>
<span class="sourceLineNo">040</span>    private final Generator&lt;T, K&gt; generator;<a name="line.40"></a>
<span class="sourceLineNo">041</span><a name="line.41"></a>
<span class="sourceLineNo">042</span>    private VaadinPersistentObjectListener&lt;T&gt; listener;<a name="line.42"></a>
<span class="sourceLineNo">043</span><a name="line.43"></a>
<span class="sourceLineNo">044</span>    /**<a name="line.44"></a>
<span class="sourceLineNo">045</span>     * Constructor.<a name="line.45"></a>
<span class="sourceLineNo">046</span>     *<a name="line.46"></a>
<span class="sourceLineNo">047</span>     * @param container container to populate<a name="line.47"></a>
<span class="sourceLineNo">048</span>     * @param generator object that generates the Java objects that back the {@link com.vaadin.data.Item}s in the container<a name="line.48"></a>
<span class="sourceLineNo">049</span>     * @throws IllegalArgumentException if {@code container} is null<a name="line.49"></a>
<span class="sourceLineNo">050</span>     * @throws IllegalArgumentException if {@code generator} is null<a name="line.50"></a>
<span class="sourceLineNo">051</span>     */<a name="line.51"></a>
<span class="sourceLineNo">052</span>    public PersistentObjectContainerLoader(AbstractSimpleContainer&lt;?, K&gt; container, Generator&lt;T, K&gt; generator) {<a name="line.52"></a>
<span class="sourceLineNo">053</span>        if (container == null)<a name="line.53"></a>
<span class="sourceLineNo">054</span>            throw new IllegalArgumentException("null container");<a name="line.54"></a>
<span class="sourceLineNo">055</span>        if (generator == null)<a name="line.55"></a>
<span class="sourceLineNo">056</span>            throw new IllegalArgumentException("null generator");<a name="line.56"></a>
<span class="sourceLineNo">057</span>        this.container = container;<a name="line.57"></a>
<span class="sourceLineNo">058</span>        this.generator = generator;<a name="line.58"></a>
<span class="sourceLineNo">059</span>    }<a name="line.59"></a>
<span class="sourceLineNo">060</span><a name="line.60"></a>
<span class="sourceLineNo">061</span>    /**<a name="line.61"></a>
<span class="sourceLineNo">062</span>     * Register this container as a listener on the persistent object and load the container.<a name="line.62"></a>
<span class="sourceLineNo">063</span>     * This method may only be invoked while the {@link VaadinSession} is locked by the current thread.<a name="line.63"></a>
<span class="sourceLineNo">064</span>     * If this method is invoked twice with no intervening {@link #disconnect}, this instance will<a name="line.64"></a>
<span class="sourceLineNo">065</span>     * automatically disconnect from the old {@link PersistentObject} before connecting to the new one.<a name="line.65"></a>
<span class="sourceLineNo">066</span>     *<a name="line.66"></a>
<span class="sourceLineNo">067</span>     * @throws IllegalArgumentException if {@code persistentObject} is null<a name="line.67"></a>
<span class="sourceLineNo">068</span>     * @throws IllegalStateException if there is no {@link VaadinSession} associated with the current thread<a name="line.68"></a>
<span class="sourceLineNo">069</span>     */<a name="line.69"></a>
<span class="sourceLineNo">070</span>    public void connect(PersistentObject&lt;T&gt; persistentObject) {<a name="line.70"></a>
<span class="sourceLineNo">071</span><a name="line.71"></a>
<span class="sourceLineNo">072</span>        // Sanity check<a name="line.72"></a>
<span class="sourceLineNo">073</span>        this.assertSession();<a name="line.73"></a>
<span class="sourceLineNo">074</span>        if (persistentObject == null)<a name="line.74"></a>
<span class="sourceLineNo">075</span>            throw new IllegalArgumentException("null persistentObject");<a name="line.75"></a>
<span class="sourceLineNo">076</span><a name="line.76"></a>
<span class="sourceLineNo">077</span>        // Connect<a name="line.77"></a>
<span class="sourceLineNo">078</span>        boolean needReload = false;<a name="line.78"></a>
<span class="sourceLineNo">079</span>        T root = null;<a name="line.79"></a>
<span class="sourceLineNo">080</span>        synchronized (this) {<a name="line.80"></a>
<span class="sourceLineNo">081</span>            if (this.listener != null)<a name="line.81"></a>
<span class="sourceLineNo">082</span>                this.listener.unregister();<a name="line.82"></a>
<span class="sourceLineNo">083</span>            this.listener = new VaadinPersistentObjectListener&lt;T&gt;(persistentObject) {<a name="line.83"></a>
<span class="sourceLineNo">084</span>                @Override<a name="line.84"></a>
<span class="sourceLineNo">085</span>                protected void handlePersistentObjectChange(T oldRoot, T newRoot, long version) {<a name="line.85"></a>
<span class="sourceLineNo">086</span>                    PersistentObjectContainerLoader.this.reload(newRoot);<a name="line.86"></a>
<span class="sourceLineNo">087</span>                }<a name="line.87"></a>
<span class="sourceLineNo">088</span>            };<a name="line.88"></a>
<span class="sourceLineNo">089</span>            this.listener.register();<a name="line.89"></a>
<span class="sourceLineNo">090</span>            root = persistentObject.getSharedRoot();<a name="line.90"></a>
<span class="sourceLineNo">091</span>            needReload = true;<a name="line.91"></a>
<span class="sourceLineNo">092</span>        }<a name="line.92"></a>
<span class="sourceLineNo">093</span><a name="line.93"></a>
<span class="sourceLineNo">094</span>        // Load container if there is data<a name="line.94"></a>
<span class="sourceLineNo">095</span>        if (needReload)<a name="line.95"></a>
<span class="sourceLineNo">096</span>            this.reload(root);<a name="line.96"></a>
<span class="sourceLineNo">097</span>    }<a name="line.97"></a>
<span class="sourceLineNo">098</span><a name="line.98"></a>
<span class="sourceLineNo">099</span>    /**<a name="line.99"></a>
<span class="sourceLineNo">100</span>     * Shutdown this container. This unregisters the container from the {@link PersistentObject} it was previously<a name="line.100"></a>
<span class="sourceLineNo">101</span>     * {@linkplain #connect connected} to. This method may be invoked from any thread and is idempotent.<a name="line.101"></a>
<span class="sourceLineNo">102</span>     * The associated container is not notified about any change.<a name="line.102"></a>
<span class="sourceLineNo">103</span>     *<a name="line.103"></a>
<span class="sourceLineNo">104</span>     * @throws IllegalStateException if there is no {@link VaadinSession} associated with the current thread<a name="line.104"></a>
<span class="sourceLineNo">105</span>     */<a name="line.105"></a>
<span class="sourceLineNo">106</span>    public synchronized void disconnect() {<a name="line.106"></a>
<span class="sourceLineNo">107</span>        this.assertSession();<a name="line.107"></a>
<span class="sourceLineNo">108</span>        if (this.listener != null) {<a name="line.108"></a>
<span class="sourceLineNo">109</span>            this.listener.unregister();<a name="line.109"></a>
<span class="sourceLineNo">110</span>            this.listener = null;<a name="line.110"></a>
<span class="sourceLineNo">111</span>        }<a name="line.111"></a>
<span class="sourceLineNo">112</span>    }<a name="line.112"></a>
<span class="sourceLineNo">113</span><a name="line.113"></a>
<span class="sourceLineNo">114</span>    /**<a name="line.114"></a>
<span class="sourceLineNo">115</span>     * Reload the container associated with this instance using the given {@link PersistentObject} root.<a name="line.115"></a>
<span class="sourceLineNo">116</span>     *<a name="line.116"></a>
<span class="sourceLineNo">117</span>     * @throws IllegalStateException if there is no {@link VaadinSession} associated with the current thread<a name="line.117"></a>
<span class="sourceLineNo">118</span>     */<a name="line.118"></a>
<span class="sourceLineNo">119</span>    protected void reload(T root) {<a name="line.119"></a>
<span class="sourceLineNo">120</span>        this.assertSession();<a name="line.120"></a>
<span class="sourceLineNo">121</span>        this.container.load(this.generator.generateContainerObjects(root));<a name="line.121"></a>
<span class="sourceLineNo">122</span>    }<a name="line.122"></a>
<span class="sourceLineNo">123</span><a name="line.123"></a>
<span class="sourceLineNo">124</span>    /**<a name="line.124"></a>
<span class="sourceLineNo">125</span>     * Verify there is a {@link VaadinSession} associated with the current thread.<a name="line.125"></a>
<span class="sourceLineNo">126</span>     *<a name="line.126"></a>
<span class="sourceLineNo">127</span>     * @throws IllegalStateException if there is no {@link VaadinSession} associated with the current thread<a name="line.127"></a>
<span class="sourceLineNo">128</span>     */<a name="line.128"></a>
<span class="sourceLineNo">129</span>    protected void assertSession() {<a name="line.129"></a>
<span class="sourceLineNo">130</span>        if (VaadinSession.getCurrent() == null)<a name="line.130"></a>
<span class="sourceLineNo">131</span>             throw new IllegalStateException("there is no VaadinSession associated with the current thread");<a name="line.131"></a>
<span class="sourceLineNo">132</span>    }<a name="line.132"></a>
<span class="sourceLineNo">133</span><a name="line.133"></a>
<span class="sourceLineNo">134</span>// Generator<a name="line.134"></a>
<span class="sourceLineNo">135</span><a name="line.135"></a>
<span class="sourceLineNo">136</span>    /**<a name="line.136"></a>
<span class="sourceLineNo">137</span>     * Interface used by {@link PersistentObjectContainerLoader} to derive {@link AbstractSimpleContainer} backing<a name="line.137"></a>
<span class="sourceLineNo">138</span>     * objects from a {@link PersistentObject} root.<a name="line.138"></a>
<span class="sourceLineNo">139</span>     *<a name="line.139"></a>
<span class="sourceLineNo">140</span>     * @param &lt;T&gt; type of the persistent object<a name="line.140"></a>
<span class="sourceLineNo">141</span>     * @param &lt;K&gt; the type of the Java objects that back each {@link com.vaadin.data.Item} in the {@link AbstractSimpleContainer}<a name="line.141"></a>
<span class="sourceLineNo">142</span>     */<a name="line.142"></a>
<span class="sourceLineNo">143</span>    public interface Generator&lt;T, K&gt; {<a name="line.143"></a>
<span class="sourceLineNo">144</span><a name="line.144"></a>
<span class="sourceLineNo">145</span>        /**<a name="line.145"></a>
<span class="sourceLineNo">146</span>         * Generate the Java objects that will back the {@link AbstractSimpleContainer} associated with<a name="line.146"></a>
<span class="sourceLineNo">147</span>         * a {@link PersistentObjectContainerLoader} from the given {@link PersistentObject} root.<a name="line.147"></a>
<span class="sourceLineNo">148</span>         *<a name="line.148"></a>
<span class="sourceLineNo">149</span>         * &lt;p&gt;<a name="line.149"></a>
<span class="sourceLineNo">150</span>         * This method should not modify {@code root}.<a name="line.150"></a>
<span class="sourceLineNo">151</span>         * &lt;/p&gt;<a name="line.151"></a>
<span class="sourceLineNo">152</span>         *<a name="line.152"></a>
<span class="sourceLineNo">153</span>         * &lt;p&gt;<a name="line.153"></a>
<span class="sourceLineNo">154</span>         * If the associated {@link PersistentObject} allows empty starts or stops, then {@code root} might be null.<a name="line.154"></a>
<span class="sourceLineNo">155</span>         * &lt;/p&gt;<a name="line.155"></a>
<span class="sourceLineNo">156</span>         *<a name="line.156"></a>
<span class="sourceLineNo">157</span>         * @param root updated persistent object root, or null in the case of an empty start or stop<a name="line.157"></a>
<span class="sourceLineNo">158</span>         * @return container backing objects<a name="line.158"></a>
<span class="sourceLineNo">159</span>         */<a name="line.159"></a>
<span class="sourceLineNo">160</span>        Iterable&lt;? extends K&gt; generateContainerObjects(T root);<a name="line.160"></a>
<span class="sourceLineNo">161</span>    }<a name="line.161"></a>
<span class="sourceLineNo">162</span>}<a name="line.162"></a>
<span class="sourceLineNo">163</span><a name="line.163"></a>




























































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